Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/0231—Traffic management, e.g. flow control or congestion control based on communication conditions
  • H04W28/0236—Traffic management, e.g. flow control or congestion control based on communication conditions radio quality, e.g. interference, losses or delay
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L47/00—Traffic control in data switching networks
  • H04L47/10—Flow control; Congestion control
  • H04L47/12—Avoiding congestion; Recovering from congestion
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/0205—Traffic management, e.g. flow control or congestion control at the air interface
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/0247—Traffic management, e.g. flow control or congestion control based on conditions of the access network or the infrastructure network
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/0284—Traffic management, e.g. flow control or congestion control detecting congestion or overload during communication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/0289—Congestion control
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/04—Error control
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
  • H04W28/10—Flow control between communication endpoints
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
  • H04W28/18—Negotiating wireless communication parameters
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/16—Performing reselection for specific purposes
  • H04W36/22—Performing reselection for specific purposes for handling the traffic
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/20—Control channels or signalling for resource management
  • H04W72/29—Control channels or signalling for resource management between an access point and the access point controlling device
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/02—Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
  • H04W8/04—Registration at HLR or HSS [Home Subscriber Server]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W24/00—Supervisory, monitoring or testing arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/12—Access point controller devices

Definitions

• the technical field relates to mobile data communications, and more particularly, to regulating uplink communications from mobile radio terminals in a radio access network.
• next generation wireless communication systems may offer high speed downlink packet access (HSDPA) and high speed uplink packet access (HSUPA) to provide enhanced data rates over the radio interface to support Internet access and multimedia type applications.
• HSDPA high speed downlink packet access
• HSUPA high speed uplink packet access
• Enhanced uplink data communications will likely employ fast scheduling and fast hybrid automatic repeat request (HARQ) with soft combining in the radio base station.
• HARQ hybrid automatic repeat request
• HARQ hybrid automatic repeat request
• the radio base station can set an upper limit on the data rate and/or transmission power that the mobile terminal may use to transmit over an enhanced uplink data channel.
• the "bottleneck" may well occur further upstream from the radio interface in the transport of the uplink information between nodes in the radio access network (RAN).
• the available uplink bit rate over the interface between a radio base station node in the RAN and a radio network controller node in the RAN (referred to as the Iub interface) may be a fraction of the available uplink bit rate over the radio interface.
• high speed uplink packet access may overload the Iub interface between the radio base station and the radio network controller during peak bit rates.
• Figure 1 illustrates that even though the downlink HSDPA bit rate over the radio interface is higher than the uplink HSUPA bit rate, the available bandwidth for high speed packet access data between the radio network controller and the radio base station is even less than the uplink HSUPA bit rate.
• the dashed line representing Iub High Speed Packet Access (HSPA) bandwidth limit is lower that the HSDPA and HSUPA bandwidths.
• a radio base station (sometimes referred to as a "Node B" using 3GPP terminology) controls three cells that have an enhanced uplink data transmission capability. Assume that the radio base station is connected to a radio network controller using one 4 Mbps link to support the enhanced uplink data transmitted from the radio base station and the radio network controller.
• the enhanced uplink capability may be up to 4 Mbps per cell.
• enhanced uplink communication data from three cells at or near capacity cannot be transported from the radio base station to the radio network controller over the single 4 Mbps link.
• the result is a congested or overload situation.
• This congestion could result in long delays and loss of data, which reduces quality of service.
• One possible solution to avoid this kind of overload situation would be to "over provision" the bandwidth resources in the radio access network for communications between radio network controllers and radio base stations. But this is inefficient, costly, and in some existing mobile communications networks, not practical.
• an HSDPA flow control algorithm could be employed by the radio base station to reduce the available downlink HSDPA bit rate to a level that suits the Iub interface bandwidth.
• Congestion associated with transporting in the RAN uplink information originating from one or more mobile terminals is detected. That detected congestion is then reduced using any suitable technique(s) and may be implemented in one or more nodes in the RAN.
• One advantageous (but non-limiting) application is to a RAN that supports high speed uplink packet access (HSUPA) and/or one or more enhanced uplink dedicated channels (E-DCHs).
• Uplink congestion may be detected over an interface between a radio network controller and a radio base station (the Iub interface) and/or an interface between radio network controllers (the Iur interface).
• congestion reduction may be performed in any suitable fashion
• one example approach is to reduce a parameter associated with a bit rate at which uplink mobile terminal information is transported through the RAN.
• the bit rate parameter may be reduced by reducing a bit rate of one or more uplink data flows. It may be appropriate to limit the bit rate of the one or more uplink data flows actually causing the congestion in the RAN; alternatively, the bit rate of one or more lower priority uplink data flows may be reduced.
• bit rate parameter may be reduced.
• a bit rate parameter value may correspond to an absolute bit rate parameter value or a relative bit rate parameter value sent to one or more mobile terminals, e.g., a maximum bit rate or transmission power or a percentage or fraction of a current bit rate or transmission power.
• Another approach is to reduce the bit rate parameter using a capacity limitation message. If the RNC detects a congested condition in the RAN, it can send a capacity limitation to a radio base station, which then schedules uplink transmissions from mobile terminals to effect that capacity limitation, e.g., by using scheduling grants or credits. [0010] In some situations, more drastic measures may be necessary to reduce the bit rate parameter such as dropping one or more frames of one or more uplink mobile terminal communications.
• one or more of the diversity handover links may be released to reduce the bit rate parameter.
• Another technique employs sending negative acknowledgment messages for received packets back to the mobile terminal causing the mobile terminal to retransmit those negatively acknowledged packets. This effectively reduces the uplink bit rate through the RAN.
• the congestion control may be implemented by sending control information either over a separate control signaling channel or in a user data plane where the control signaling is sent along with the data over a data channel.
• FIGURE 1 is a graph illustrating the high speed packet access bandwidth for both the uplink and downlink directions as compared to the RAN bandwidth;
• FIG. 2 is a block diagram of a mobile communications system including an example radio access network (RAN) ;
• RAN radio access network
• Figure 3 is a diagram illustrating various uplink chancels used by mobile terminals for communicating over the radio/air interface with the RAN;
• Figure 4 is a function block diagram illustrating various interfaces between multiple nodes in a radio access network
• Figure 5 is a flow chart diagram illustrating example steps for uplink RAN congestion detection and control
• Figure 6 is a function block diagram illustrating one example implementation for uplink RAN congestion detection and control
• Figure 7 illustrates a capacity limitation message being sent from the RNC to the radio base station to reduce detected congestion or load in the RAN.
• Figure 8 is a diagram illustrating a mobile terminal in soft handover in which a weaker soft handover leg is dropped in order to reduce uplink RAN congestions.
• Network 10 may accommodate one or more standard architectures including a universal mobile telecommunications system (UMTS) and other systems based on code division multiple access (CDMA), GPRS/EDGE and other systems based on time division multiple access (TDMA) systems, etc.
• UMTS universal mobile telecommunications system
• CDMA code division multiple access
• GPRS/EDGE time division multiple access
• TDMA time division multiple access
• CDMA Code Division Multiple Access
• different wireless channels are distinguished using different channelization codes or sequences, (these distinct codes are used to encode different information streams), which may then be modulated at one or more different carrier frequencies for simultaneous transmission.
• a receiver may recover a particular stream or flow for the receive signal using the appropriate code or sequence to decode the received signal.
• TDMA the radio spectrum is divided into time slots. Each time slot allows only one user to transmit and/or receive. TDMA requires precise timing between the transmitter and the receiver so that each user may transmit its information during its allocated time slot.
• the network 10 includes a radio access network (RAN) 14 and one or more core network(s) 12.
• RAN radio access network
• UTRAN UMTS terrestrial access network
• Core network 14 typically supports circuit-based communications as well as packet-based communications.
• the RAN 14 includes one or more radio network controllers (RNCs) 16. Each RNC is coupled to one or more radio base stations (RBSs) 18 sometimes referred to as Node B's.
• RNCs radio base stations
• the communications interface between Node Bs and RNCs is referred to as the Iub interface, and the communications interface between RNCs is referred to as the Iur interface.
• Transport of information over the Iub and Iur interfaces is typically based on asynchronous transfer mode (ATM) or Internet Protocol (IP).
• ATM asynchronous transfer mode
• IP Internet Protocol
• Wireless terminals 20 communicate over an air or radio interface with the RAN 14.
• the radio interface is referred to as the Uu interface.
• the two center mobile terminals are shown communicating with both RBSs 18.
• HSDPA high speed downlink packet access
• HSUPA high speed uplink packet access
• E-DCH enhanced uplink dedicated channel
• Enhanced uplink employs several uplink channels from each mobile terminal with an active uplink connection as illustrated in Figure 3.
• the enhanced dedicated physical data channel (E- DPDCH) carries enhanced uplink data (at higher bit rates), in addition to the normal dedicated physical data channels (DPDCHs) used for regular uplink data communication.
• the dedicated physical control channel (DPCCH) carries pilot symbols and out-of-band control signaling.
• Out-of-band control signaling related to enhanced uplink e.g., uplink scheduling requests, may be carried on the enhanced dedicated physical control channel (E-DPCCH).
• Each aggregation node (1) aggregates data traffic from the RBSs to the RNCs and (2) splits the data traffic from the RNCs to the individual RBSs.
• there are multiple Iur and Iub interfaces which may have limited bandwidth capability.
• Some type of congestion control should be in place to avoid congestion, delay, and overload situations caused by receiving uplink data over the radio interface at a rate greater than what can be currently transported over any one of these RAN interfaces.
• Congestion is monitored in the RAN that is associated with transporting uplink information through the RAN (step S2).
• An overload or congestion condition is detected between nodes in the RAN related to uplink information for example by detecting frame (or other data unit) losses (step S4).
• Frame losses may be detected using a frame sequence number (FSN).
• FSN frame sequence number
• Each transport bearer between an RNC and a radio base station has its own sequence number. It is assumed that when a frame sequence number is detected as missing, that the corresponding frame is lost due to congestion.
• delay build-up can be monitored to detect a congestion condition. In transport networks that include large buffers, congestion may not normally result in frame losses, but rather in a build-up of delay time in the buffer before packets are transmitted.
• each user plane frame transmitted from a base station uplink to an RNC includes a field for a real-time stamp, e.g., a control frame number (CFN) plus a subframe number.
• a real-time stamp e.g., a control frame number (CFN) plus a subframe number.
• CFN control frame number
• the RNC detects a time stamp "drift," meaning that the delay is increasing, the RNC can then determine there is congestion. For example, if uplink frames are delayed more than 30 msec in addition to the delay that is prevailing in non-congested circumstances, this is a good indicator of uplink congestion in the RAN.
• step S6 one or more actions is taken to reduce the detected uplink congestion in the RAN.
• the RNC 16 includes an uplink RAN congestion detector 30 and uplink RAN congestion controller 32, and a handover controller 34.
• the RNC 16 includes other functional entities which are not pertinent to this description and therefore are not shown.
• the radio base station 18 includes an uplink RAN congestion controller 40, an automatic repeat request (ARQ) controller 42, (which in a preferred implementation is a hybrid ARQ (HARQ) controller), a mobile terminal uplink scheduler 44, and radio circuitry 46.
• the radio base station 18 has other entities and circuitry for performing the functions not pertinent to the description and therefore are not shown.
• the uplink RAN congestion detector 30 monitors and detects uplink RAN congestion using, for example, frame loss detection or delay build-up detection as described above. Other techniques may be employed.
• the uplink RAN congestion controller 32 processes congestion detection information provided by detector 30, and based on certain characteristics of one or more congested uplink flows, the uplink RAN congestion controller 32 may decide to limit the uplink load in the RAN using any suitable methodology.
• the congestion controller 32 may limit a maximum data rate/transmission power grant that the mobile terminal uplink scheduler 44 is allowed to assign to a particular mobile terminal or to a mobile terminal uplink data flow.
• the mobile terminal subjected to this maximum data rate/power restriction can be the same mobile terminal or data flow which is experiencing the congestion on one or more flows, or it may be a different mobile terminal or data flow, perhaps with a lower priority.
• the uplink RAN congestion controller 32 may limit the maximum data rate/transmission power that the uplink scheduler 44 is allowed to assign to a group of mobile terminals.
• the uplink RAN congestion controller 32 may communicate the maximum data rate/transmission power to the radio base station 18 using a CAPACITY LIMITATION message, as illustrated in Figure 7.
• the CAPACITY LIMITATION notification message includes the maximum bit rate/power that the uplink scheduler 44 may assign to one or more mobile terminal uplink flows.
• the CAPACITY LIMITATION message may also include a time interval over which the maximum bit rate/power restriction applies. On the other hand, the limits may remain in effect until a new capacity limitation message is received.
• the uplink CAPACITY LIMITATION notification may be sent either in the RAN "user plane” using a control frame embedded with the data or in the RAN “control plane” using control signaling over an explicit control channel.
• Example control signaling protocols includes Node B Application Part (NBAP) /RNS Application Part/RNSAP).
• the maximum bit rate/power may be expressed, for example, as an absolute limit, such as 200 Kbps, or as a prohibition from using a transport format indicator (TFI) exceeding a particular value, such as TFI 12.
• An example in terms of an absolute transmission power might be a maximum allowed transmission power offset, and an example of a relative limit might be a percentage by which to reduce the current bit rate/power, e.g., 50%.
• the load may be reduced with respect to the affected mobile terminal, an affected uplink flow, an aggregated load of multiple mobile terminals, or different mobile terminals or different flows that are less prioritized than the affected one(s).
• the congestion controller 40 may limit the scheduling grants assigned to a particular mobile terminal or group of mobile terminals.
• a mobile terminal can be connected to multiple cells controlled by one or several radio base stations. Of the cells in this "active set," the strongest (in terms of a pilot signal) is typically chosen as the "serving cell" responsible for the primary control of the mobile terminal. Via this serving cell, the radio base station can assign absolute grants limiting the maximum bit-rate/power of the mobile terminal. In order to control the inter-cell interference, the radio base stations can also send relative grants via non-serving cells.
• Relative grants indicate if one or a group of mobile terminals should increase, hold, or decrease their current bit-rate/power. Any of these grants can be based on scheduling requests sent in the uplink from the mobile terminal to the radio base-stations. Such scheduling requests typically include, e.g., the desired bit-rate or the present buffer fill-levels in the mobile terminal. [0033] In the situation where the radio base station controls the serving cell of the mobile terminal, the uplink RAN congestion controller 40 limits the absolute grant of that mobile terminal; alternatively, the uplink RAN congestion controller 40 assigns relative grants (up/hold/down) so that the RNC capacity limitation is fulfilled. The uplink scheduler 44 can provide scheduling information to the mobile terminal to control the upper limit of the mobile terminal transmission data rate/transmission power.
• the “absolute grant channel” may carry an absolute scheduling grant on a shared channel which includes (a) the identity of the mobile terminal (or a group of mobile terminals) for which the grant is valid and (b) the maximum resources that this mobile terminal (or group of mobile terminals) may use.
• a “relative grant channel” carries a relative scheduling grant on a dedicated channel and includes at least one bit that registers an incremental up/hold/down.
• the absolute grant channel is read from the serving cell.
• the relative grant channel may be read from additional cells, e.g., in the case of soft handover, from all cells in the active set.
• the uplink RAN congestion controller 40 assigns relative grant indications (up/hold/down) to fulfill the RNC capacity limitation.
• the uplink RAN congestion controller 40 may discard RAN data frames so that the RAN capacity limitation assigned by the RNC is fulfilled without affecting scheduling grants.
• the uplink RAN congestion controller 40 may instruct the H/ ARQ controller 42 to send a NACK message for each received and discarded data unit back to the mobile terminal. NACKing the discarded data frames from a non-serving cell triggers re-transmission of those discarded data frames, unless some other link has received those data frames correctly. The effect is reduced pressure on the RAN transport.
• the uplink RAN congestion controller 32 may restore the original data rate or transmission power by sending notification to the radio base station.
• a configurable or predefined period of time may be set after which the temporary restriction on the uplink scheduler 44 is released. This latter approach may be preferred because explicit signaling from the RNC is not required.
• the congested radio link L3 is not the "serving" handover link.
• the serving link is the strongest one of the handover links based on detected signal strength measurements.
• the uplink RAN congestion controller 32 may decide to release the weaker handover radio link L3, which is subject to congestion in the RAN, and leave links Ll and L2. This congestion reduction approach has the benefit of not affecting the bit rate over the radio interface. Any capacity loss associated with loss of macro-diversity over the air interface is less impacting than the RAN congestion associated with link L3.
• the RAN Iub and Iur interfaces each likely have a maximum total uplink bandwidth. A certain, relatively small amount of each maximum bandwidth is allocated for control signaling.
• the RNC detects uplink congestion over one of the interfaces, it sends a message to the RBS to reduce the enhanced uplink dedicated data channels bandwidth by a certain percentage selected to reduce the congestion without impacting the enhanced uplink services too much.
• the enhanced uplink dedicated data channels bandwidth may be restored to Y.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Databases & Information Systems (AREA)
• Quality & Reliability (AREA)
• Mobile Radio Communication Systems (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=36677913

Family Applications (1)

Country Status (8)

Cited By (32)

Families Citing this family (107)

Citations (5)

Family Cites Families (27)

• 2005
  • 2005-01-14 US US11/035,021 patent/US7724656B2/en active Active
  • 2005-12-23 TW TW094146394A patent/TWI370644B/zh active
• 2006
  • 2006-01-10 CN CNA2006800021321A patent/CN101124838A/zh active Pending
  • 2006-01-10 WO PCT/SE2006/000032 patent/WO2006075951A1/en active Application Filing
  • 2006-01-10 EP EP06700655.1A patent/EP1836866B1/en active Active
  • 2006-01-10 BR BRPI0606600-3A patent/BRPI0606600B1/pt not_active IP Right Cessation
  • 2006-01-10 CN CN201310054092.7A patent/CN103152765B/zh not_active Expired - Fee Related
  • 2006-01-10 KR KR1020077016074A patent/KR20070094781A/ko not_active Application Discontinuation
  • 2006-01-10 JP JP2007551220A patent/JP5021498B2/ja active Active
• 2010
  • 2010-03-11 US US12/659,509 patent/US20100232293A1/en not_active Abandoned
• 2013
  • 2013-12-02 US US14/094,083 patent/US20140086057A1/en not_active Abandoned
• 2015
  • 2015-02-18 US US14/624,606 patent/US20150163693A1/en not_active Abandoned

Patent Citations (5)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events